The need for cooling has increased in various applications due to higher heat flux densities resulting from newly developed electronic devices, being, for example, more compact and/or higher power than traditional devices. An example of this is UHP (Ultra High Performance) lamps and LED (Light Emitting Diode) lamps, where the performance and lifetime is often limited by the heat developed.
In addition to natural convection, fans, either traditional propellers or synthetic jet coolers, can be utilized to enhance the heat transfer by forced convection. A typical synthetic jet actuator is disclosed in U.S. Pat. No. 6,123,145, comprising a housing having a flexible controllable diaphragm. As the diaphragm moves the volume in the chamber changes and vortices are ejected from the chamber through the orifice. The generated synthetic jet stream can impinge on a heated surface thereby cooling this surface.
However, disadvantages associated with prior art are noise, fouling, additional cost, limited lifetime, power dissipation, as well as extra space and weight. As lighting applications are particularly demanding on all these issues (compared to e.g. microprocessors in computers), lighting customers and suppliers are reluctant to accept/introduce active cooling by forced convection. Thus, there is a need for improved active cooling by forced convection.